Surface sediments and bivalves were collected from the Changjiang Estuary in December 2003 and November 2004, respectively. Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in these samples were mea...Surface sediments and bivalves were collected from the Changjiang Estuary in December 2003 and November 2004, respectively. Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in these samples were measured with high-resolution chromatography (HRGC)/High Resolution Mass Spectrometer (HRMS). The concentrations of total PCDD/Fs and toxic equivalent (TEQ) were 169.83±119.63 and 0.81±0.36 pg/g dry weight (dw) in sediments, and 580.33±240.17 and 7.24±3.65 pg/g dw in bivalves. The homolog compositions of PCDD/Fs were similar among samples, the most abundant congener was octa-chlorinated dibenzo-p-dioxin (OCDD) and then octa-chlorinated dibenzofuran (OCDF) and 1,2,3,4,6,7,8-hepta-chlorinated dibenzo-p-dioxin (HpCDD). The herbicide pentachlorophenol (PCP) and sodium pentachlorophenol (Na-PCP) were proved the main source of PCDD/Fs in this area.展开更多
The oxidation behavior of three biodiesels of different origins,viz.rapeseed oil derived biodiesel,soybean oil derived biodiesel and waste oil based biodiesel,were tested on an oxidation tester.The chemical compositio...The oxidation behavior of three biodiesels of different origins,viz.rapeseed oil derived biodiesel,soybean oil derived biodiesel and waste oil based biodiesel,were tested on an oxidation tester.The chemical compositions of the biodiesels were characterized by gas chromatography.Thereafter,the structural transformation of fatty acid methyl ester(FAME)of the biodiesels was analyzed by an infrared spectrometer and an ultraviolet absorption spectrometer.The results demonstrated that the oxidation behavior of biodiesels of different origins was closely related to the composition and distribution of FAMEs.Higher concentration of unsaturated FAME with multi-double bonds exhibited poorer oxidation resistance.Furthermore,cis-trans isomerization transformation occurred in the unsaturated FAME molecules and conjugated double-bond produced during the oxidation process of biodiesel.Greater cis-trans variations corresponded to deeper oxidation degree.The higher the content of unsaturated FAME with multi-double bonds in a biodiesel,the more the conjugated double bonds was formed.展开更多
A sensitive and specific high performance liquid chromatography （HPLC） method was developed and validated for the simultaneous determination of metformin hydrochloride （HCI） in human plasma. The HPLC method consis...A sensitive and specific high performance liquid chromatography （HPLC） method was developed and validated for the simultaneous determination of metformin hydrochloride （HCI） in human plasma. The HPLC method consists of isocratic eluation with a mixture of 60% buffer （10 mM sodium dihyrogenphosphate-10 mM sodium dodecyl sulphate） and 40% acetonitrile with final pH 7.0 with flow rate of 1.0 mL/min on a Kromasil~ Akzo Nobel RP-18 （4.6 mm ID ~ 250 mm, 5 ~tm） column at an ambient temperature. Photo diode array detection was performed in program mode at 234 rim. The analyte and diazepam as internal standard （IS） were extracted from plasma using 10% trichloroacetic acid. The assay was linear over the therapeutic concentration range of 20-2,500 ng/mL for metformin HCI with correlation coefficient of r = 0.9999. Limit of quantitation was 20 ng/mL. The results obtained for intraJinter day accuracy and precision complied very well with the generally accepted criteria for bio-analytical assay. The method was applied to bioequivalence （BE） study of metformin HCI in healthy Indonesian volunteers after treatment with 750 mg XR metformin HCI. This BE study shows that the two formulations are equivalent so that they were therapeutically interchangeable for each other.展开更多
As an effective and universal acaricide, amitraz is widely used on beehives against varroasis caused by the mite Varroa jacobsoni. Its residues in honey pose a great danger to human health. In this study, a sensitive,...As an effective and universal acaricide, amitraz is widely used on beehives against varroasis caused by the mite Varroa jacobsoni. Its residues in honey pose a great danger to human health. In this study, a sensitive, rapid, and environmentally friendly surface-enhanced Raman spectroscopy method (SERS) was developed for the determination of trace amount of amitraz in honey with the use of silver nanorod (AgNR) array substrate. The AgNR array substrate fabricated by an oblique angle deposition technique exhibited an excellent SERS activity with an enhancement factor of -10^7. Density function theory was employed to assign the characteristic peak of amitraz. The detection of amitraz was further explored and amitraz in honey at concentrations as low as 0.08 mg/kg can be identified. Specifically, partial least square regression analysis was employed to correlate the SERS spectra in full-wavelength with Camitraz to afford a multiple-quantitative amitraz predicting model. Preliminary results show that the predicted concentrations of amitraz in honey samples are in good agreement with their real concentrations. Compared with the conventional univariate quantitative model based on single peak’s intensity, the proposed multiple-quantitative predicting model integrates all the characteristic peaks of amitraz, thus offering an improved detecting accuracy and anti-interference ability.展开更多
The determination method of chlorogenic acid in traditional Chinese prescription Shuanghuanglian capsule was established by using quantitative nuclear magnetic resonance spectroscopy(q NMR) in combination with solid p...The determination method of chlorogenic acid in traditional Chinese prescription Shuanghuanglian capsule was established by using quantitative nuclear magnetic resonance spectroscopy(q NMR) in combination with solid phase extraction(SPE). As the capsule’s main active component, chlorogenic acid comes from the extraction of Chinese herb medicine Flos Lonicerae. The chlorogenic acid in capsule was ultrasonically extracted at room temperature using pure water as solvent. The extracting solution was enriched and cleaned using HC-C18 SPE cartridge. The effect of ultrasonic extraction, sample pretreatment conditions via SPE and q NMR experimental conditions were investigated. The q NMR experiment conditions were selected using deuterated DMSO as solvent, calibrated 1,4-phthalaldehyde as internal standard, and P1(pulse width) = 14.4 μs, d1(pulse delay time) = 1 s, NS(number of scan) = 512. The 1 H NMR peaks of δ 6.138–6.182(H-8’, d, 1 H) of chlorogenic acid was chosen as the quantitative peaks. Method validation was performed, including precision(the intra-day RSD = 1.2% and the inter-day RSD = 1.5%), linearity(correlation coefficient r>0.9999), LOD(0.0017 mg/g) and LOQ(0.079 mg/g). The recovery of the SPE-q NMR was within the range of 100.2%–103.2%. The result showed that the method was stable, accurate and reliabile. Determined by the method, the chlorogenic acid in a real Shuanghuanglian capsule was within the range of 9.68–10.35 mg/g.展开更多
基金The project supported by National Natural Science Foundation of China under Grant No. 10371070 and the Special Funds for Major Specialities of Shanghai Education Committee
文摘Bilinear form of the nonisospectral AKNS equation is given. The N-soliton solutions are obtained through Hirota＇s method.
基金supported by National Research Program (No. 2003CB415005)"Youth Chen-Guang Project" of Wuhan Bureau of Science and Technology (No. 200750731259).
文摘Surface sediments and bivalves were collected from the Changjiang Estuary in December 2003 and November 2004, respectively. Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in these samples were measured with high-resolution chromatography (HRGC)/High Resolution Mass Spectrometer (HRMS). The concentrations of total PCDD/Fs and toxic equivalent (TEQ) were 169.83±119.63 and 0.81±0.36 pg/g dry weight (dw) in sediments, and 580.33±240.17 and 7.24±3.65 pg/g dw in bivalves. The homolog compositions of PCDD/Fs were similar among samples, the most abundant congener was octa-chlorinated dibenzo-p-dioxin (OCDD) and then octa-chlorinated dibenzofuran (OCDF) and 1,2,3,4,6,7,8-hepta-chlorinated dibenzo-p-dioxin (HpCDD). The herbicide pentachlorophenol (PCP) and sodium pentachlorophenol (Na-PCP) were proved the main source of PCDD/Fs in this area.
基金the financial support from the National Natual Science Foundation of China(No.51375491)the Natural Science Foundation of Chongqing(Project No.2011JJA90020)the Science Foundation for Young Teachers of Logistical Engineering University
文摘The oxidation behavior of three biodiesels of different origins,viz.rapeseed oil derived biodiesel,soybean oil derived biodiesel and waste oil based biodiesel,were tested on an oxidation tester.The chemical compositions of the biodiesels were characterized by gas chromatography.Thereafter,the structural transformation of fatty acid methyl ester(FAME)of the biodiesels was analyzed by an infrared spectrometer and an ultraviolet absorption spectrometer.The results demonstrated that the oxidation behavior of biodiesels of different origins was closely related to the composition and distribution of FAMEs.Higher concentration of unsaturated FAME with multi-double bonds exhibited poorer oxidation resistance.Furthermore,cis-trans isomerization transformation occurred in the unsaturated FAME molecules and conjugated double-bond produced during the oxidation process of biodiesel.Greater cis-trans variations corresponded to deeper oxidation degree.The higher the content of unsaturated FAME with multi-double bonds in a biodiesel,the more the conjugated double bonds was formed.
文摘A sensitive and specific high performance liquid chromatography （HPLC） method was developed and validated for the simultaneous determination of metformin hydrochloride （HCI） in human plasma. The HPLC method consists of isocratic eluation with a mixture of 60% buffer （10 mM sodium dihyrogenphosphate-10 mM sodium dodecyl sulphate） and 40% acetonitrile with final pH 7.0 with flow rate of 1.0 mL/min on a Kromasil~ Akzo Nobel RP-18 （4.6 mm ID ~ 250 mm, 5 ~tm） column at an ambient temperature. Photo diode array detection was performed in program mode at 234 rim. The analyte and diazepam as internal standard （IS） were extracted from plasma using 10% trichloroacetic acid. The assay was linear over the therapeutic concentration range of 20-2,500 ng/mL for metformin HCI with correlation coefficient of r = 0.9999. Limit of quantitation was 20 ng/mL. The results obtained for intraJinter day accuracy and precision complied very well with the generally accepted criteria for bio-analytical assay. The method was applied to bioequivalence （BE） study of metformin HCI in healthy Indonesian volunteers after treatment with 750 mg XR metformin HCI. This BE study shows that the two formulations are equivalent so that they were therapeutically interchangeable for each other.
基金supported by the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province (No.16KJB510009 and No.17KJB510017)Jiangsu Province Natural Science Foundation of China (BK20150228)
文摘As an effective and universal acaricide, amitraz is widely used on beehives against varroasis caused by the mite Varroa jacobsoni. Its residues in honey pose a great danger to human health. In this study, a sensitive, rapid, and environmentally friendly surface-enhanced Raman spectroscopy method (SERS) was developed for the determination of trace amount of amitraz in honey with the use of silver nanorod (AgNR) array substrate. The AgNR array substrate fabricated by an oblique angle deposition technique exhibited an excellent SERS activity with an enhancement factor of -10^7. Density function theory was employed to assign the characteristic peak of amitraz. The detection of amitraz was further explored and amitraz in honey at concentrations as low as 0.08 mg/kg can be identified. Specifically, partial least square regression analysis was employed to correlate the SERS spectra in full-wavelength with Camitraz to afford a multiple-quantitative amitraz predicting model. Preliminary results show that the predicted concentrations of amitraz in honey samples are in good agreement with their real concentrations. Compared with the conventional univariate quantitative model based on single peak’s intensity, the proposed multiple-quantitative predicting model integrates all the characteristic peaks of amitraz, thus offering an improved detecting accuracy and anti-interference ability.
基金National Natural Science Foundation of China(Grant No.31671928)Natural Science Foundation of Shanghai(Grant No.15ZR1440800).
文摘The determination method of chlorogenic acid in traditional Chinese prescription Shuanghuanglian capsule was established by using quantitative nuclear magnetic resonance spectroscopy(q NMR) in combination with solid phase extraction(SPE). As the capsule’s main active component, chlorogenic acid comes from the extraction of Chinese herb medicine Flos Lonicerae. The chlorogenic acid in capsule was ultrasonically extracted at room temperature using pure water as solvent. The extracting solution was enriched and cleaned using HC-C18 SPE cartridge. The effect of ultrasonic extraction, sample pretreatment conditions via SPE and q NMR experimental conditions were investigated. The q NMR experiment conditions were selected using deuterated DMSO as solvent, calibrated 1,4-phthalaldehyde as internal standard, and P1(pulse width) = 14.4 μs, d1(pulse delay time) = 1 s, NS(number of scan) = 512. The 1 H NMR peaks of δ 6.138–6.182(H-8’, d, 1 H) of chlorogenic acid was chosen as the quantitative peaks. Method validation was performed, including precision(the intra-day RSD = 1.2% and the inter-day RSD = 1.5%), linearity(correlation coefficient r>0.9999), LOD(0.0017 mg/g) and LOQ(0.079 mg/g). The recovery of the SPE-q NMR was within the range of 100.2%–103.2%. The result showed that the method was stable, accurate and reliabile. Determined by the method, the chlorogenic acid in a real Shuanghuanglian capsule was within the range of 9.68–10.35 mg/g.
